JPH095381A - Method for inspecting connection between liquid crystal panel and drive circuit element - Google Patents

Abstract

PURPOSE: To obtain a convenient method for inspecting defect of TAB(Tape Automated Bonded) in an LCD(Liquid Crystal Display) in which the TAB is formed using an ACF(Anisotropic Conductive Film). CONSTITUTION: Inspection terminals 24 are arranged contiguously to a group of input terminals 14 arranged on the substrate 10 side and inspection leads 27 are arranged contiguously to a group of leads 17 arranged on the flexible tape 16 side. After formation of TAB, conduction is inspected between both pads 25, 28 and if they are short-circuited, position of the lead 17 is shifted significantly due to elongation of the flexible tape 16 and a decision is made that there is a connection failure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a TAB (tape aut) for connecting a liquid crystal panel and a driver LSI for driving the same.
In omated bonding), the present invention relates to a TAB structure capable of finding defects by a simple inspection and its inspection method.

[0002]

2. Description of the Related Art As a display device, a liquid crystal display device (LCD: Liquid Crystal Display) using a liquid crystal as an optical member.
play) has advantages such as small size, thin shape and low power consumption.
Practical application is progressing in the fields of A equipment, AV equipment, and the like. In particular, a matrix type in which transparent electrodes for driving liquid crystal are arranged in a cross manner and a voltage is applied while selecting display points in a matrix,
Furthermore, the active matrix type, in which a switch element is connected to each pixel capacitor for liquid crystal driving and the signal voltage is electrostatically always held while line-sequentially selecting rewriting pixels, is a high-definition, high-contrast type. It has become possible to display moving images in a ratio, and has been put to practical use in personal computer displays, televisions, etc.

FIG. 3 is an equivalent circuit diagram of the LCD. (1)
Is a gate line for a scanning line, (2) is a drain line for a signal line, and a thin film transistor (TFT: thin film) which is a switching element is provided at the intersection of both lines (1, 2).
transistor) (3) is formed. Reference numeral (4) is a pixel capacitance for driving the liquid crystal, which is connected to the TFT (3). Gate line (1) and drain line (2)
Are formed on the same substrate and are driven by drivers (5, 6), respectively. A display electrode forming one side of the pixel capacitance (4) is connected to the source of the TFT (3), and a common electrode forming the other side of the pixel capacitance (4) is formed on another substrate which is arranged to face the liquid crystal in between. There is. A high voltage is selectively applied to the gate line (1) in a line-sequential manner, so that the T lines in the same row are
The FTs (3) are turned on all at once, and in synchronization with this, an image signal voltage is applied from the drain line (2) and held in the pixel capacitance (4).

FIG. 4 is an overall view of such an LCD as seen from above, and FIG. 5 is a sectional view taken along the line AA. A substrate (10) on which TFTs (3) and the like are formed and a substrate (11) on which a common electrode is formed are bonded together, liquid crystal (12) is sealed in the space between them, and a sealing material (13) is used at the periphery. A hermetically sealed liquid crystal panel is constructed.
Input terminals (14) for the gate line (1) and the drain line (2) are formed at the ends of the substrate (10) and are exposed on the surface. A gate or drain driver LSI (15) is bonded and mounted on a flexible tape (16) such as polyimide, and a printed circuit board (18) on which an input terminal (14) and a control circuit are formed by a lead wire (17) made of Cu foil. ) Is connected to. The conductor (17) and the terminal (14) are connected by ACF (anistropic).
conductive film) (19), that is, an anisotropic conductive film in which conductive particles are dispersed in an adhesive. Also. The conductor (17) and the wiring on the printed circuit board (18) are connected by solder (20). Such a driver L
The method of mounting SI (15) is TAB (tape automated bond
ing).

FIG. 6 is an enlarged plan view of a conventional TAB connecting portion. A wiring (21) for a gate line or a drain line is extended from the display portion formed by adhering the substrate (11) to the end portion of the substrate (10), and each line is connected to each input terminal (14). It is connected. At the end where the group of input terminals (14) is arranged, the ACF (1
A flexible tape (16), in which the ends of conductors (17) connected to the driver LSI (15) are arranged in an array, is sandwiched with 9) therebetween.

FIG. 7 is a sectional view taken along the line BB of FIG. The ACF (19) is, for example, a film having a thickness of about 20 μm in which conductive particles (23) formed by plating a resin ball with gold are dispersed in an epoxy resin adhesive (22).
The input terminal (14) on the substrate (10) and the conductive wire (17) on the flexible tape (16) are aligned, and by heating under pressure, in the portion where the input terminal (14) and the conductive wire (17) face each other, The conductive particles (23) contact each other to form an electrical connection between the input terminal (14) and the lead wire (17).

[0007]

[Problems to be Solved by the Invention]
The connection according to (19) is formed in two steps.
That is, first, at a temperature of 50 ° C to 100 °, input terminals (1
4) and the conductor (17) while aligning the substrate (1
0) and the flexible tape (16) are pressed and fixed by temporary pressure bonding, and then 130 ° C to 200 ° C.
The resin is cured by thermocompression bonding at °, and main compression bonding is performed.

For this reason, the flexible tape (16) made of polyimide is stretched during the heating of the main pressure bonding even if the positioning is performed during the temporary pressure bonding, and the positions of the input terminal (14) and the conductive wire (17) are increased. There was a problem of slippage. That is, as shown in FIG.
When 6) extends in the lateral direction, the conductor wire (17)
The position of shifts as well and shifts from the input terminal (14) to be connected. Therefore, the connection between the input terminal (14) and the conducting wire (17) is poor, or the input terminals (1
4) and the conducting wire (17) are erroneously connected.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve this problem, and is a liquid crystal in which a liquid crystal is sealed between a pair of electrode substrates on which electrode wiring for driving the liquid crystal is formed. A third substrate on which a drive circuit element is mounted is adhered to the panel, and an input terminal formed on an end portion of the electrode substrate and connected to the electrode wiring and the drive circuit formed on the third substrate. In a method of inspecting a connection between a liquid crystal panel and a driving circuit element, which electrically connects a lead wire connected to an output terminal of an element, a predetermined distance is provided at an end portion of the electrode substrate in a group in which the input terminals are arranged Inspection terminals adjacent to each other are formed, and inspection conductors adjacent to the group of the conductors arranged at a predetermined distance are formed on the third substrate, and the inspection terminals and the inspection terminals are formed. Depending on whether there is electrical continuity with the conductor A determining arrangement the quality of the connection of the input terminal and the conductor.

Further, in particular, the electrical connection between the inspection terminal and the inspection conductor wire determines the connection failure between the input terminal and the conductor wire.

[0011]

With the structure of the present invention, in the present invention, the terminals for inspection and the wires for inspection are arranged side by side in a group in which the terminals for driving and the wires for driving are arranged on the liquid crystal panel substrate and the third substrate, respectively. After fixing both boards and fixing both boards, the quality of the connection between the driving terminal and the conducting wire can be easily determined by simply checking the connection between these testing terminals and the conducting wire. By moving to the process and returning the defective product to the previous process,
The step of fixing the substrate and the third substrate can be redone. In this way, since the connection status of both boards can be easily inspected, the process of moving to the next process, finding a defect, and returning it to the previous process are all performed quickly, which reduces manufacturing costs and reduces economic costs. Efficiency is improved.

[0012]

FIG. 1 is an enlarged plan view of a TAB forming portion according to an embodiment of the present invention. On the substrate (10), from the display portion on which a display electrode for driving a TFT or a liquid crystal is formed,
A wiring (21) of a gate line or a drain line has been extended, and each line is connected to the input terminal (14) or is integrally formed with this. Dummy terminals (26) are formed continuously in a group in which these input terminals (14) are arranged, and further, inspection terminals (24) are arranged and formed at the same pitch. Inspection terminal (24)
Are integrally formed with the inspection pad (25).

On the other hand, on the flexible tape (16) made of polyimide, a conductive wire (17) connected to the driving LSI (15) is formed, and each wiring (2) on the substrate (10) is formed.
They are arranged so as to correspond to 1). In addition, the conducting wire (2) for inspection is continuously connected to the group in which the conducting wire (17) is arranged.
7) is arranged and formed, and the inspection pad (28) is formed integrally therewith.

In both of these substrates (10, 16), the band in which the ends of the conductors (17) are arranged overlaps the band in which the input terminals (14) are arranged with the ACF (19) in between. Input terminal (1
4) and the conductive wire (17) face each other, the conductive particles in the epoxy resin forming the ACF are in contact with each other to form an electrical connection.

At the time of this heating, the flexible tape (16) made of polyimide stretched, and the flexible tape (1) was aligned despite the initial alignment.
The position of the end of the lead wire (17) shifts as the length of 6) increases. That is, as shown in FIG. 2, even if the input terminal (14) and the conducting wire (17) are aligned during the first heating at the low temperature of the temporary crimping, the conducting wire is heated at the second heating at the high temperature of the main crimping. The position of (17) does not move, for example, the lead wire (1
7) is not only disconnected from the input terminal (14) that is supposed to be connected, but is also erroneously connected to the adjacent input terminal (14), and an incorrect signal is applied to the wiring (21). The problem arises.

According to the present invention, the connection between the input terminal (14) and the lead wire (17) can be assessed by performing an open / short test between the test pads (25) and (28) after forming the TAB. . That is, flexible tape (1
6) is extended, and the inspection wire (2
When the position of 7) is displaced and reaches the inspection terminal (24), current is conducted between both pads (25, 28). Therefore, the incorrect connection can be determined by optimally setting the position of the inspection terminal (24) based on the line widths of the input terminal (14) and the conductive wire (17) and the pitch thereof. That is, in this embodiment, the input terminal (14) and the dummy terminal (2
6) and the inspection terminals (25) are arranged at the same pitch, and the conductor wires (17) and the inspection conductor wires (27) are also arranged at the same pitch, so that the inspection conductor wires (27) that are most displaced from the original position are moved. ) Is used as a criterion for judging the quality of the deviation from the dummy terminal (26) to be originally connected to reach the adjacent inspection terminal (24).

Such an input terminal (14) and a conductor (1
The problem of erroneous connection of 7) is not detected only by a normal open / short inspection because a voltage is applied unless there is a defect in the panel itself, and is recognized only when a fine moving image is displayed. Therefore, since it is a serious defect, the inspection cannot be simplified and the work efficiency of the inspection is poor.

According to the present invention, such an erroneous connection between the input terminal (14) and the lead wire (17) is simply detected by the inspection pad (25).
The work efficiency is high because it can be found by a simple inspection method that only checks the conduction between (28). In addition, the gist of the present invention is
The present invention is not limited to the above-mentioned embodiments, and depending on the line width and pitch of the input terminal (14) and the conductive wire (17),
That is, when the line width is smaller than the space between lines, the dummy terminal (26) and the inspection terminal (24) are made to be the same, and the connection failure is determined by the opening between the pads (25) and (28). It is also possible to do so.

[0019]

As is apparent from the above description, according to the present invention, by providing predetermined inspection pads on the liquid crystal panel side and the TAB side, respectively, it is easy to check the conduction between both pads after the TAB is formed. Incomplete inspection finds a bad connection. Therefore, after the quality is judged, the non-defective product can be immediately transferred to the next process, and the defective product can be immediately transferred to the previous process, so that workability is improved.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of a TAB connecting portion according to an embodiment of the present invention.

FIG. 2 is an enlarged plan view showing a TAB connection inspection method according to an embodiment of the present invention.

FIG. 3 is an equivalent circuit diagram of a liquid crystal display device.

FIG. 4 is an overall top view of a liquid crystal display device.

5 is a cross-sectional view taken along the line AA of FIG.

FIG. 6 is an enlarged view of a conventional TAB connection portion.

FIG. 7 is a sectional view taken along the line BB of FIG. 6;

FIG. 8 is an enlarged plan view showing a problem of the conventional TAB connection method.

[Explanation of symbols]

 1 gate line 2 drain line 3 TFT 4 pixel capacity 5 gate driver 6 drain driver 10, 11 substrate 12 liquid crystal 13 sealing material 14 input terminal 15 driver LSI 16 flexible tape 17 conductive wire 18 printed board 19 ACF 20 solder 21 wiring 22 adhesive 23 Conductive particles 24 Inspection terminals 25, 28 Inspection pads 26 Dummy terminals 27 Inspection conductors

Claims (2)

[Claims] 1. A third substrate on which a drive circuit element is mounted is adhered to a liquid crystal panel in which a liquid crystal is sealed between a pair of electrode substrates on which electrode wiring for driving the liquid crystal is formed. Driven by a liquid crystal panel, electrically connecting an input terminal formed at an end of an electrode substrate and connected to the electrode wiring, and a lead wire formed on the third substrate and connected to an output end of the drive circuit element. In the circuit element connection inspection method, at the end of the electrode substrate, an inspection terminal is formed adjacent to the group in which the input terminals are arranged at a predetermined distance.
On the third substrate, an inspection conductive wire that is adjacent to the group in which the conductive wires are arranged at a predetermined distance is formed, and whether or not there is electrical conduction between the inspection terminal and the inspection conductive wire,
A method for inspecting a connection between a liquid crystal panel and a drive circuit element, which comprises determining whether the connection between the input terminal and the conductor is good or bad. 2. The liquid crystal panel according to claim 1, wherein the connection failure between the input terminal and the conductor is determined by the electrical connection between the inspection terminal and the conductor. Circuit element connection inspection method.